Prudence requested or prudence required

Saturday

May 5, 2007 at 12:01 AM

David Holmes

With a tad more than two inches of rain received in April, and none since the evening of April 18, it is once again shaping up to be a dry spring. Early one Sunday morning in April we received .85 inch, but that afternoon windy conditions quickly dried out the topsoil, making much of that rain ineffective.
Because May is typically a dry month, we should expect no relief until the arrival of the traditional summer rains, sometime in early to mid-June.
This lack of rain exasperates the problem of a short water supply that already exists in Central Florida. Plants, and particularly lawns, and more specifically lawns with St Augustine grass are probably going to suffer if people do what they're supposed to.
Residents of Marion County live in one of two water management districts. Generally Interstate 75 is a boundary line, with those living east of I-75 residing in the St. Johns River Water Management District and those living west of I-75 residing in the Southwest Florida Water Management District.
Each of these districts have established guidelines (or in the words of the regulators - restrictions) for watering. These are not suggested practices, but rather rules for lawn irrigation; violation can result in fines. Those who live in the St. Johns District are currently limited to watering 2 days per week (you choose your days to water) and no watering between 10 a.m. and 4 p.m. Those in the Southwest Florida District are limited to watering one time per week and properties less than two acres may not water between 8 a.m. and 6 p.m. while larger properties may not water between 10 a.m. and 4 p.m. If your address number ends in 0 or 1, water Monday; if 2 or 3, water Tuesday; if 4 or 5, water Wednesday; if 6 or 7, water Thursday and if 8, 9 or indiscernible, water Friday.
There are many factors that enter into decisions about when to water. Variables include soil type and condition, type of grass, rainfall and temperatures and whether grass is in partial shade or full sun. Lawns should be irrigated when about half of the lawn shows signs of wilt.
These signs include: leaf blades are folded in half lengthwise in an attempt to conserve water; looking across the lawn, it begins to take on a blue-gray tint; footprints or tire tracks remain visible on the grass long after being made.
Before irrigating, always check the weather forecast. Avoid watering if rain is forecast within the next two days. Plan for irrigation to occur in early morning and never early evening or before 5 a.m.
So, based on our projected dry spring, what general guidelines can a homeowner follow for his/her lawn? In normal circumstances, within the guidelines established above, for St. Augustine grass, the University of Florida recommends two applications of three-fourths of an inch of water per week.
In instances where restrictions limit the number of times water may be applied, one inch to one and one-half inch one time per week would be the recommendation. During these stressful drought days, mowing height should be maximized, allowing grass to remain at a four inch length. Minimize mowing to two times per month, cutting to a three inch height, to maximize weed control.
For those residents fortunate enough to have bahia grass lawns, no irrigation is needed. Observe local pastures - this turf will go dormant in drought conditions. It will green up almost immediately at the first appearance of the summer rains.
It seems likely water will continue to be an issue for lawns in years to come, whether dry conditions exist or not. It is no secret that St. Augustine grass likes water - lots of it!
For those who desire alternatives, consider gradual reduction of turf areas and replacement with drought-tolerant ground covers.
Next week this column will consider ground covers that perform well in drought conditions.
One of the videos my children have enjoyed over the years is a take-off on Cinderella. Living in a droughty California neighborhood, the selfish wicked stepmother repeatedly disregarded watering restrictions, even though neighbors complied. In one scene, an aerial view of the neighborhood, her lawn stands out as the only oasis in an otherwise brown landscape. The scene comes to my mind as I wonder how many green lawns will prevail over the next four to six dry weeks.
David Holmes is director of the Marion County Extension Service (University of Florida Institute of Food and Agricultural Sciences).